Winged hull for a watercraft

ABSTRACT

A hull for a boat, for example a sailboat, has a sharply angled front or bow with a curved center crest line providing a entry into the water during forward motion. Sides of the bow are concave. The main body of the hull is shaped as a semicircle in transverse cross section. The upper edge of the hull has a flare that extends laterally outward to form wings along both sides of the hull. The wings begin adjacent the front or bow and gradually increase in the extent of their lateral extension at a mid-position the hull and adjacent the stern. The stern has an angled end extending rearward at the bottom of the hull. A step is provided at the stern. The deck extends from the upper edge of the hull to the edges of the cockpit. The cockpit has curved inside surfaces and a center beam extending along the center of the boat, the center beam having sloping surfaces. An open transom permits water to flow from the cockpit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a winged water surface craft hull, andin particular to a winged hull for a sailboat or powerboat or otherwatercraft utilizing a winged hull shape.

2. Description of the Related Art

People have been moving about on the surface of lakes and seas withsuccess for perhaps 10,000 years or more. Ocean dwelling creatures, onthe other hand, are the genetic result of a few million years ofnature's evolutionary natural selection survival process and so have asignificant ‘research and development’ head start when it comes tomoving about in water. Thus, it is likely that large fast fish orwater-based mammals are almost perfectly optimized for moving largebodies efficiently in the water. A better understanding of how whales,sharks, dolphins and other large-bodied ocean creatures move soeffortlessly and rapidly in an incompressible fluid, and apparently withsuch low energy consumption, may be the best strategy to rapidly improvewatercraft technology.

By definition surface watercraft operate at the interface of two quitedissimilar fluids—air and water. This interface can change from friendlylight waves and winds, to powerful life-threatening squalls or evenlarge tsunami-like water wave disturbances sometimes with little or nowarning.

Most likely the safest and best watercraft operating today are modernnaval craft and in particular submarines and aircraft carriers. Thesafest place at sea in a storm or major tidal wave is below the surfacesuggesting submarines have the greatest potential for survival of allwatercraft. The modern aircraft carrier is probably the best adaptedman-made surface watercraft, because it is designed to operate on thesurface in hurricanes and is often forced to do so to avoid potentialdamage in port. Such large complex and costly military craft representone extreme end of the spectrum in the current state of the art inwatercraft. At the other end of the spectrum there remains theopportunity to develop low cost but much safer and more efficientwatercraft designs to meet normal pleasure and transport needs.

Since many of us travel on water at least once in a while, and we putour lives at a higher level of risk when offshore in a surfacewatercraft, it would seem reasonable that in addition to the practice ofcarrying personal floatation devices and even life rafts on board, awatercraft should itself possess high levels of designed-in watersurvival capability.

The inventor suggests that watercraft design requirements should includesome of the desirable capabilities listed below:

-   -   1. Unsinkable even with multiple hull breaches or when capsized,    -   2. Operable at some reasonable efficiency even after suffering        multiple hull breaches,    -   3. Unsinkable even with hull severed in a catastrophic event        through floatation of any major severed sections.

Meeting any of these requires that first the craft, together withoccupants and maximum payload, be significantly lighter than water.Second, the craft must be designed to eliminate the possibility of anydangerous level of swamping, so that even after suffering one or morehull breaches, it can still operate at an adequate level of efficiencyto return its crew and passengers to safety without outside help.

Amazingly enough, very few pleasure or even professionally crewedpassenger surface craft operating today can meet the first two of thesesuggested basic survival requirements. Hardly any craft, including navyvessels, can meet the third requirement. Although many watercraftinclude some level of emergency floatation, most will become swamped andvirtually incapable of normal operation, or navigation through the waterafter suffering a major hull breach or taking on large waves that filledthe interior of the craft. This is because, even if the craft does notsink, the high level of swamping accepted in most designs will usuallyfill the craft, lowering it to the gunnels in the water. Such a swampedcondition would make the craft difficult to move and may leave the craftand its occupants at the mercy of the seas.

A notable exception to this situation is the Boston Whaler surfacecraft. These boats are foam-filled, eliminating the quite common butvery dangerous potential risk of water swamping the craft throughdisplacement of the interior air with water following a hull breach orentry of large swamping waves.

This situation has prevailed in the industry over many years, mostlikely because use of floatation foam, balsa, cork or similar materialsto eliminate swamping or sinking increases cost and reduces the hullvolume available for crew and payload.

Whatever the reason for the current situation, sinking or swamping maybe eliminated through a change in design priorities for watercraft, asamply demonstrated by the Boston Whaler. A craft using adequate foam orother floatation techniques may end up some 30% or so larger for thesame payload. Although more costly, such craft will offer much improvedsafety for crew and payload, and a much greater chance of survival underall but perhaps the most severe sea conditions. As an important sidebenefit, a craft so designed could have potential for higher speedbecause of its approximately 30% increased waterline length.

A surface craft has the task of working well at the interface of bothwater and air under a wide range of weather conditions. This is adifficult task, and one not optimized in any large bodied livingcreature that comes to mind. Large fish and whales are believed to avoidthe surface during storms. Seabirds trapped at sea during storms aretypically forced to abandon flying and set down on the water surfaceusing their wings slightly open to trap air and improve balance andflotation in a rolling seaway.

Clearly, fish and birds have evolved to a very high level of performancejudged by their speed and maneuverability in their respective water orair environments. The inventor has attempted to draw clues for efficientunderwater hull shapes from the body shapes of large fast-moving fish ormammals such as dolphins, sharks and killer whales. Similarly, theshapes of birds in flight offer valuable clues to optimizing above-watershapes. The further optimization of surface craft hull design toincrease efficiency in moving through the water and to take advantage ofthe natural action of the water being displaced by the hull follows inthe body of the text.

When it comes to the mechanics of moving efficiently on the water'ssurface there are several key characteristics of the large-bodied fastfish we may wish to emulate. The first and probably most important isthe body shape. The large fish and mammals such as sharks and dolphinshave hulls with a nominally circular cross section with maximum bodydiameter roughly in the middle and tapering more or less to a pointtowards either end. There is a well-defined sharp point at the front forwater separation, a powerful but slender tail at the rear for propulsionand several fins attached to the main body. The round body shape willhave very low roll resistance, the creature relying on its fins and tailfor directional control and stability. This tapered circular hull shapepermits the creature to move in water with the minimum of resistance andtherefore the least amount of energy expended.

In keeping with fish shapes virtually all watercraft are tapered to apoint at the bow, but are usually cut off straight at the stern, andthus are bullet shaped when viewed from above. This blunt cut-off at thestern is likely to increase stern wave generation and increase drag,when compared to a tapered stern. Interestingly, circular cross sectiontapered hulls, while used in submarines and torpedoes, are often avoidedin surface craft, particularly powered craft, because of their low rollresistance. Rolling on a seaway is uncomfortable to people, and surfacecraft typically design-in higher roll resistance through a variety ofdifferent underwater shapes, such as flat bottoms or chines, to avoidexcessive rolling or capsizing. However, most current watercraftdesigns, although possessing relatively high static and dynamic rollresistance when level or heeled at lower heel angles, often exhibit thepotentially dangerous characteristic of reduced roll resistance withincreased heel angle when heeled beyond some critical angle. This leavessuch craft exposed to a higher risk of swamping or capsizing in heavyseas.

The current invention attempts to reverse this situation through a hullthat has little or no roll resistance for low drag at normal heelangles, but through the use of extended wings built into the upper hullsides, exhibits dramatically higher roll resistance at higher heelangles. Thus, the winged hull of the current invention will resistdangerous over heeling and potential capsizing at extreme heel angles.

In general, sailboat hulls are more efficient than power boat hulls inmoving through or displacing water with low resistance because they mustoperate in light winds. Power boats, on the other hand, can justincrease engine power and bum more fuel to overcome hull designinefficiencies. Also, sailboats are widely considered safer in heavyweather and high seas because their deep keels and sails stabilize themotion of the boat greatly in comparison to most power boat designs.

Although these hull design principles are equally applicable to bothpower and sail craft, any hull design efficiency improvements are likelybest demonstrated in a sailboat hull. Superior speed or lower fuelconsumption in a power boat may be due to other factors such as engineefficiency. Sailboat hull efficiency is easily demonstrated in sailboatraces through superior performance of the new designs over others ofsimilar size under the same wind conditions.

Small to midsized sailboats are quite popular among recreational sailorswho like to spend a day on the water racing or just sailing about,usually on protected bodies of water or near the shore. Theserecreational sailboats are often small enough to be brought to thewater, for example, on a trailer pulled behind a vehicle. Many differingdesigns of small sailboats are available for the recreational sailor.These sailboats enable the recreational sailor to enjoy a day of sailingand potentially to compete against others in sailing contests, thusimproving their craft handling and other sailing skills. The sailorsthat crew these boats may be experienced and expert sailors, but morecommonly are occasional sailors who do not have all the skills andexperience of a more seasoned sailor. Less experienced sailors are oftenunaware of and unprepared to handle the extremely hazardous conditionsthat can occur with little or no warning in squalls or storms.

A danger of many of the available smaller sailboats is that they mayperform poorly in a seaway or under heavy air conditions. Speed ofmotion is critical in a surface craft because speed is required forcontrol. Only when the craft is moving can the crew have any control onthe direction and attitude of the craft. Once at rest the craft isentirely at the mercy of the wind and sea. Many sailors therefore prefersailboats that are faster and more maneuverable, handle more smoothly,and perform well in a wider variety of weather conditions, making theday on the water safer and more enjoyable.

SUMMARY OF THE INVENTION

The present invention provides in one embodiment a hull for a sailboat,which has low drag and is safe, fast and fun under a significantly widerrange of weather conditions than other craft of its size. The hull isshaped to more closely optimize the action of hydrodynamic forces of thewater acting on the hull, and in effect work with, not against, thewater to improve the motion, speed and stability of the boat. Ingeneral, the portion of the hull below the water line emulates a largefish to provide optimum hydrodynamic effects. At the same time, theportion of the hull above the water line more emulates seabird shapes toprovide aerodynamic and hydrodynamic effects and other functionsspecific to optimum sailing performance.

Although this hull shares general shapes common to many other sailboatdesigns, particularly when viewed from a distance at the side or fromabove, there are key differences that result in critical safety andperformance improvements that are the subject of this invention. Thesekey hull differences may be visually evident when viewed up close, outof the water or, when underway directly from the bow or stern.

Specifically, the hull has a sharply defined water entry line withwater-flow shaping surfaces extending from the water entry line at thebow. The shaping at the bow changes to a mid-portion of the hull havinga generally semicircular transverse cross section to permit the boat toreadily roll, or heel, when under sail.

The stern, or back of the hull, has an extension to provide an increasedwater line length for greater speed and to transfer weight forward, andshaped for minimum stern wave generation and low stern drag. Above thewater line, the hull has extensions, or wings, extending from the uppersides of the hull. The extensions or wings are small to non-existent atthe bow or front of the boat but extend to a greater length from thesides of the hull. The extensions or wings are shaped to contact thewater surface only at large heel angles.

The crew space of an embodiment of the present hull has an open transomto permit any water entering the cockpit to exit the cockpit easily andautomatically while the boat is under sail. The interior surfaces of thehull are shaped to provide seating surfaces and foot braces for the crewat a variety of heel angles while sailing. The deck surface extends overthe extensions or wings at the sides of the boat to provide seating forthe crew during large heel angles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation illustration a design principle fora bow of a hull according to the present invention in front view;

FIG. 2 is a schematic representation illustrating a design principle ofthe bow of the present hull in side view;

FIG. 3 is a schematic representation of a design principle of atransverse cross section of a mid portion of the present hull below thewater line;

FIG. 4 is a schematic representation of a design principle of the sternof the present hull, shown in side view;

FIG. 5 is a schematic representation of a design principle of sides ofthe present hull at and above the water line, in transverse crosssection;

FIG. 6 is a schematic representation of a design principle for an upperbow of the present hull, in side view;

FIG. 7 is a perspective view of a sailboat including a sailboat hullincorporating the foregoing design principals of the present invention;

FIG. 8 is a view of the stern of an alternative embodiment showing arearward tapering extension;

FIG. 9 is a bottom perspective wireframe drawing of the hull, slightlyfrom the side;

FIG. 10 is a side perspective wireframe drawing of the present sailboathull;

FIG. 11 is an enlarged end perspective view of the present sailboat hullshowing the stern;

FIG. 12 is a top end perspective view of the sailboat hull showing thecrew compartment;

FIG. 13 is a schematic partial view of a the interior construction ofthe hull in cross section;

FIG. 14 is a photograph of a prototype sailboat having a hull accordingto the principles of the present invention in bow view;

FIG. 15 is a photograph of the prototype sailboat in side view;

FIG. 16 is a photograph of the prototype sailboat in front view;

FIG. 17 is a photograph of the prototype sailboat broaching;

FIG. 18 is a photograph of the prototype sailboat generally from therear showing a trough formed in the water;

FIG. 19 is a photograph of the prototype sailboat generally from theside;

FIG. 20 is a photograph of the prototype sailboat from the front andshowing the shaping of the water at the bow;

FIG. 21 is a photograph of the prototype sailboat from the front quartershowing the boat sailing in light wind;

FIG. 22 is a perspective view of the present hull with a zebra stripeenvironmental mapping pattern overlaid thereon so enhance contours ofthe hull shape;

FIG. 23 is a photograph of the present sailboat shown from the frontport side; and

FIG. 24 is the photograph of FIG. 23 on which is overlaid the Zebrastripe environmental mapping.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The sailboat hull of the present invention utilizes hydrodynamic shapingto provide a performance sailboat hull that moves quickly andefficiently through the water. A preferred embodiment of a moreoptimized hull is demonstrated in an 18 foot sailboat. A front portionof the hull has a shape to ease water entry and to shape the water flowat the front of the boat. FIG. 1 shows a schematic representation of thewater entry portion of the present hull in transverse cross section(also see FIG. 14 that shows the present embodiment prototype sailboatfrom the bow view). FIG. 2 shows this same water entry portion of thehull in the longitudinal starboard side view. In particular, the waterentry includes a relatively sharp edge 22 that slices into the water.

The sharp edge 22 is followed by a pair of outwardly angled concavesurfaces 24. These outwardly angled concave surfaces 24 receive anddirect the water that is sliced by the edge of the bow and direct it notonly up and out but also impart a curve to the water flow at entry, asshown by arrows E. These curved water flows formed over the bow surfacestravel through the air in a ballistic path back to the water surface andtend to encourage the formation of vortices in the water on either sideof the hull 20, as shown by arrows V. The vortices V, once started bythe shape of the bow, continue to move along the two sides of the hullas the hull moves through the water (see FIG. 15 wherein the vortex,normally hidden under the hull side wings is in this instance clearlyvisible because the boat is rolled to weather rather than to leeward bythe larger action of the seaway).

As mentioned, the water is displaced or splashed aside by the sharp bowand then follows a curved ballistic path back to the surface. The convexshape of the hull at the bow and along the sides of the hull under thewings is designed to approximate this ballistic path of the water beingdisplaced by the hull at higher speeds, and therefore minimizesunnecessary re-contact with the water and associated unnecessarilyhigher drag.

The key characteristics of this unique hull shape are more clearlyillustrated in FIG. 22 showing so-called zebra stripes, which arecontour lines rendered by the 3D CAD software program used to developthe hull. These zebra stripes are generated by modeling in a so-calledenvironmental mapping process which models light reflecting of the hullssurface from a grid of alternatively colored and white horizontalcontrasting bars. The resulting wide zebra stripes exaggerate the hullsurface contours and more clearly illustrate the lines of leastcurvature and therefore may predict the path that water could beexpected to take as it is displaced by the moving hull.

FIG. 23 is a photograph of the prototype sailboat of the currentinvention underway from ahead and to the port side. This photographclearly shows the wave shape generated by the hull moving through thewater at moderate speed. As illustrated in FIG. 24, when narrow zebrastripes independently created by the computer generated environmentalmapping of the hull such as shown in FIG. 22 are overlaid on thephotograph of FIG. 23, it becomes apparent that the stripes do in factclosely map the actual path taken by water being displaced.

Furthermore, in comparing the zebra stripe model with other pictures ofthe boat underway at high speed but showing the entire side of the hullrather than just the front portions shown in FIG. 23, the zebra stripesappear to closely match the hull displacement wave shape not only at thesharply contoured bow, but also over the entire length of the hull.

As a result of carefully creating this sympathetic streamlined hullshape shown in FIG. 22, drag from water in contact with moving hull isminimized, and therefore the forces required from the sails to move theboat are also minimized. All drag from the moving hull in contact withthe water takes energy from the hull and acts as a braking force. Whencompared with many existing hull designs a smoother more efficient waterflow results with lower associated drag.

There are several other “winged” sailboat hull designs within the stateof the art which properly require differentiation from the currentinvention. These winged designs fall in to a small group ofexceptionally high performance boats that perform to a great degree likelarge windsurfers. One such design is the Australian 18 Skiff designedby Julian Bethwaite. This craft is sailed by experts only and is one ofthe fastest sailing dinghies in the world. The boat is very light andcarries a massive sail area when compared with any other 18 foot boat.The high heeling forces from the sails are countered by crew on trapezesclimbing up large hiking nets or wings built in to the sides and angledup from the deck. This technique gains extreme leverage from the crewhiking forces.

Because of the Australian 18's tremendous power-to-weight ratio, it iscapable of very high speeds in strong breezes, and can plane upwind evenin light breezes. These so-called “crash and burn” designs are oftenseverely damaged in sailing accidents and collisions during racing.Their wings increase heeling moment of the crew as with the currentinvention, but are not normally intended to enter the water, and sincethe wings are just open nets mounted on angled frames they do not sharethe other important features of the current invention.

Several other slightly less extreme winged sailing dinghies exist in thestate of the art, and most notably those from Bethwaite Design, theleading Australian racing dinghy design company. One such design withwings is the “79er” which like the Australian 18 is also a very highperformance planing dinghy and, although not requiring a trapeze forhiking, is also designed for experts only. The 79er wings are anintegral part of the hull, and therefore appear somewhat similar to thecurrent invention when viewed from the stern. The 79er therefore alsoproperly requires full differentiation from the current invention. Aswith the Australian 18, the 79er's wings have one primary purpose, whichis that of increased crew leverage. The 79er's wings do not accomplishand are not designed to accomplishing the other design goals of thecurrent invention, and as will be apparent from the followingdiscussion, the present hull represents a departure from the 79erdesign.

In one embodiment, the front water line entry portion of the presenthull continues for about the first one fourth of the hull length. Otherfractions may also be use.

In side view, the water line entry portion 22, as shown in FIG. 2, has acurved shape with a substantial horizontal component to the curve. Thistraditional “spoon bow” curved shape 20 has a benefit over many modern“plumb bow” configurations in which the front edge of a hull issubstantially perpendicular to the water line, and generally used tomaximize waterline length (and therefore displacement speed potential).Waves hitting a spoon bow tend to lift the bow of the boat up to permitthe boat to ride over the wave, whereas a plumb bow tends to push intothe wave and generally results in more water washing over the deck andpossibly into the cockpit. The effects of the water, and in particular awave, are indicated in FIG. 2 as arrows W that tend to push the front ofthe hull up as indicated at arrow U.

The effect of the spoon bow shape then is to assist the boat in ridingup over waves, and to keep the front of the boat riding high. This keepsthe crew dryer and also facilitates movement of the hull up onto thewater surface to help accomplish planing of the boat at speed. Althoughperhaps less ideal, particularly for in-shore craft, a hull with a plumbbow is also envisaged in a further embodiment and within the intendedscope of this invention.

The foregoing describes the front portion of the hull. At a middleportion or main body 26 of the hull, the hull has a transverse crosssection that is generally semi-circular, as shown in FIG. 3, or at leasttending to a semi-circular shape. The semi-circular cross sectionpermits the hull to roll readily about its longitudinal axis, offeringlittle resistance from the water. The roll directions are indicated bythe double-ended arrow R. Many boat hulls are built with structures toresist rolling, including squared or angled corners, so-called chines,channels, and the like. The present hull departs from this and offersthe rounded cross section 26 so that it rolls easily, like a log in alog roll. This helps to minimize hull resistance in a seaway andtherefore absorb less energy from the boat when rolling, leaving moreenergy available to propel the boat forward.

The hull is designed to work like the body of a large fish, which aspreviously noted has a nominally round body shape with very low rollresistance, relying for control and stability on its fins and tail.Similarly, this semicircular hull shape has almost no static rollresistance at rest, and any heeling force is only countered by thecounterbalancing efforts of the crew, and the ballast weight and motiondamping effects of the centerboard (or keel). However, roll resistanceincreases dramatically, even when at rest, once the heel angle issufficient to place the vestigial side wings in the water.

The boat develops dynamic stability underway because of the liftingforces from the centerboard (an underwater wing similar to a fishesfin), and the lifting forces of the sails. These forces normally act inthe same direction tending to roll the hull to leeward and are counteredby the weight of the ballasted centerboard and the balancing efforts ofthe crew weight on the windward side of the boat. Thus, dynamicstability increases with speed in a similar way to that of a bicycle,which has no stability at rest, but can be easily held stable at speedthe rider balancing with his movements to correct for roll.

The semi-circular shape of the mid-portion 26 of the hull may includevariations in the radius of curvature, such as having a shorter radiusof curvature at a portion midway along the hull and a longer radius ofcurvature in cross sections closer to the rear of the boat. This has aflattening effect that may tend to increase the capability of the hullto plane at speed and, to the extent that it is less circular aft, mayalso lend some level of increased roll resistance and stability for thecrew.

A transition is made between the shape of FIG. 1 and the shape of FIG. 3along the body of the boat, as will be apparent from a review of thelater figures. This transition is gradual so as to provide as littledisturbance to the water flow as possible. Similarly, the transitionfrom the semi-circular shape of a shorter radius at a middle portion ofthe boat to a semi-circular shape of longer radius is also gradual.

As show in FIG. 4, at the stern 28 of the hull an extension 30 isprovided that extends the lower portions of the hull beyond the upperportions of the hull. The extension increases the water line length ofthe boat. A boat hull that operates as a water displacement hullnormally has a limit on the speed that the hull can obtain. The limitdepends on the water line length of the hull, for example according tothe following. The theoretical maximum speed for a boat with a singledisplacement hull is 1.34 (L_(WL))^(1/2), where L_(WL) is the length infeet of the hull at the water line. At this speed, the bow wave andstern wave coincide to form a continuous wave system and trap adisplacement boat in its own wave. By increasing the waterline length,the boat can go faster while moving as a displacement hull.

In one embodiment, the present hull is 18 feet in length, although otherlength hulls are of course possible. The 18 foot sailboat in its presentembodiment has a waterline length of approximately 17 feet, andtherefore a maximum displacement speed of about 5.5 knots. This maximumdisplacement speed can be overcome as the boat climbs up on its own bowwave; that is, as the boat planes. By incorporating features thatfacilitate planing and in common with other planing craft, the presentboat can exceed the speed limit for a displacement hull.

The extension 30 of the hull at the stern 28 also has the effect ofmoving the crew space forward, so that the weight of the crew is movedaway from the stern and closer to the midway point between the bow andstern. The weight of the boat hull is also moved forward by theextension, which effectively trims off weight at the end of the boat.The boat rides better in the water as a result.

In a further embodiment intended to be within the scope of the presentinvention, the stern extension 30 may also run further aft as shown inFIG. 8. In this embodiment the stern hull extension is lengthened toallow the smooth “fish body” hull shape to continue aft until it risesabove the normal waterline, and so more closely emulates the body shapeof a large fish moving on the surface. In the first embodiment of theinvention, the hull was cut-off at 18 feet to provide a convenientvertical mounting surface for the rudder. However, this vertical edgehas the downside of creating a small stern wave when in motion as aresult of water rushing in to fill the air space behind the verticalsurface. The result is increased hull drag.

The inventor expects that extending the natural fish hull shapeillustrated in FIG. 8 to completely, rather than partially, clear thewaterline at the stern will further increase the efficiency of the hull.It is anticipated that the associated increase in wetted surface dragfrom further extending the stern may be more than offset by theelimination or at least further reduction in stern wave creation. Withthis added extension the hull becomes similar to the traditionalso-called “double-ender” hull designs that have fallen out of fashion inlarger craft, but remain the standard in man-powered canoes and rowingskulls.

So far, the discussion of the hull has addressed the shapes of theportion of the hull in the water. As noted, this portion of the hullemulates the body of a large fish, and as such is shaped for optimummovement through the water. In common with virtually all other sailboatdesigns the portion of the hull that normally lies above the water is ofa shape designed to move efficiently through air, and so has shapes withlow cross sectional areas presented to the wind as with a bird inflight. Surfaces above the water are therefore kept as flat as possibleto reduce air drag. With the exception of the mast required to carry thesails, bluff surfaces are avoided since they carry a very high air dragburden. Clearly, a sailboat's sails act as the equivalent of wings on abird and deliver the same lift and power functions.

Unlike other sailboats this hull has an additional similarity to birds,because of the built in vestigial wings on the upper hull sides. Thesewings act in a similar manner to a seabird's wings, which as notedpreviously are held slightly open when at rest on the water surface totrap air, and thereby both add buoyancy and improve stability when theseabird sits on a rolling sea. The wings are formed by flared sides thatextend laterally from the upper portion of the hull. As shown in FIG. 5(and in FIG. 16 which shows the wings extending from the sides of thecraft), the flares or wings 32 are curved outward in a reverse curvefrom the semi-circular curve 26 of the hull bottom.

The wings 32 serve several key purposes, one of which is to provide abroader deck surface for the crew as with the 79er, enabling the crew tomove outward from the center line of the boat. Such movement providesleverage for control of heeling movement, without the necessity ofpresenting an undesirably wider canoe body to the water. This isaccomplished by the crew sitting on the sides of the deck over thewings. The wings 32 also provide a hull surface that contacts the waterat higher heeling angles to oppose further heeling, or tipping, of theboat. These flares or wings 32 are not in the water while the boat is atrest or underway at normal heel angles, and although creating someincrease in air drag because of the larger cross section and surfacearea presented to the air, do not increase the hull water drag.

The flares or wings 32 are at their greatest extent at the sides of thehull. The outward flare of the hull decreases to its minimum extent atthe bow 34, as shown in FIG. 6. The presence of a flare at the bow of aboat has the effect of preventing the water from splashing up into theboat and so is used in many power boat hull designs. However, it alsocatches the force of an upwardly directed wave and can slow the boatdown or lift the front of the boat more than desired if a particularlystrong wave strikes the boat, possibly even enough to be flipped over bya large wave in very heavy seas. As such, the present hull has little orno flare 36 at the bow 34 and in the area of the front of the boat. Thepresent hull therefore minimizes the braking effect of bow flare uponentering wave-fronts.

These principles of hull design may be combined in different ways toprovide hulls of different shapes, all of which fall within the scope ofthe present invention. The hull can be longer or shorter as needed. Asnoted, one such hull has a length of 18 feet. However, the hull designprinciples described above may be extended to a hull of several hundredfeet or more. The longer the boat, the more effective and efficient thishull shape will be. As boat length increases boat width does not need toincrease in the same proportion. A boat 18 feet in length has typicallyabout 6 feet maximum beam. A 72 foot boat might be about 16 to 18 feetwide. Therefore, hull width typically increases at a lower rate that thehull length increases. This is because the need for hull width isdetermined by the volume needs of occupants and payload, and watercraftvolume typically increases at a greater rate than length.

As a result, a longer boat has the advantage of needing to moveproportionally less water aside than a smaller boat, allowing for alower rate of change of curvature of the hull. All this meansproportionally less drag and therefore less energy needed to move thewater aside to make way for the body of the boat. Furthermore, in verylong boats, the differing hull shapes needed at the bow, middle andstern can begin to approach the ideal. In the present 18 feet lengthembodiment the bow, middle and stern are so close together that a bestcompromise shape is all that is possible.

The forgoing principles have been brought together in a hull shape for asmall performance sailboat. FIG. 7 shows a sailboat 40 that includes ahull 42, a centerboard or keel 44, a rudder 46, and a mast 48 on whichis mounted sails 50.

The sails 50 include a primary sail or mainsail 52 supported between themast 48 and a boom 54 that extends from the mast 48, and a jib sail orjib 56 extending between the mast and the front or bow 58 of the hull42. The front of the hull 42 has the bow 58 shaped according to theprinciples show in FIGS. 1, 2 and 6. The rear of the hull 42 has a stern60 at the rear shaped according to the principles shown in FIG. 4. Thehull 10 is symmetrical about a center line 62 through which the centerboard 44 extends.

In particular, the bow 58 of the hull 42 is shaped to present a sharpedge 64 for easy entry into the water. The hull surfaces 66 at the leftside, or portside, and right side, or starboard side, of the edge 64 areconcave and angled outward, as noted above. The sharp edge 64 definesthe center line 62 of the hull 42 that runs from the tip of the bow 58back to the stern 60. The shaping of the hull 42 changes smoothly fromthe sharp angle 64 at the front with the concave sides to the morerounded or semi-circular shape at the main body portion 68 of the hull.This change in shape is done gradually in longer boats according to thisinvention, but in the illustrated 18 foot boat, the change is lessgradual since there is less hull length in which to make the transition.It is important, however, that no abrupt changes in hull shape be madeso as to maintain the low drag, efficient performance of this boat.

Referring back to FIG. 7, the upper edge of the hull 42 is provided witha rub rail 72 where the deck is attached to the hull. The upper edge ofthe hull 42 is referred to as the gunnel or sheer. When the boat 40 isproperly trimmed and sitting still in the water, the lower portion ofthe hull 42 is in the water and the upper portion of the hull is abovethe water line. The portions of the hull that are above the waterlineare referred to as the topsides, and the minimum distance from thewater-line to the gunnels or sheer line 72 is referred to as freeboard.The present hull has more freeboard than most comparable smallsailboats. The extra freeboard together with the spoon bow and sidewings permit the boat to operate in somewhat larger seas with less greenwater over the decks, and permits greater heeling before water entersthe cockpit area. The hull 42 of FIG. 7 includes the wings 74 which aredescribed as individual features in FIGS. 5 and 6.

The portion of the hull 42 just below the rail is shaped to provide thewings 74 extending laterally outward from the center plane of the boat.The wings 74 are formed to gradually increase in the extent of flare,from little or no flare adjacent to the bow 58, to an increasing extentof lateral projection from portions of the hull 42 at the middle andrear portion of the boat.

In common boating terms, a flare is an outward curve of a vessel'ssides, usually near the bow. In the present invention, by contrast, theflare does not project much or at all near the bow of the boat, butinstead has its greatest outward extension from hull's sides 78 at theback half of the boat. The flares are referred to as wings 74 in thepresent boat and are clear of the water while sailing on lower wind at ashallow heel angle. However, at larger heel angles, the wing 72 on theside of the boat toward which the boat is heeling (the leeward side)contacts the water where the buoyancy and drag of the wings in waterresists further heeling and stabilizes the boat. In hull 42 of theillustrated embodiment, the boat heels readily to a fifteen degree angleor more from vertical without contact of the wings 74 with the water.

While sailing, the sailboat 40 heels over (or rolls to the side) as aresult of the wind forces on the sails 50 and 52. With a small tomoderate angle of heel, the bottom 68 and sides 78 of the hull are inthe water, to present a relatively narrower, sleeker hull shape andthereby reduce water drag and enable more rapid movement through thewater. The semi-circular shape of the mid-body and rear portion of thehull enables the boat to heel over easily to a fifteen degree or greaterangle. The ease with which this boat heels when stationary or at lowspeeds may feel unsettling to less experienced sailors but is the key toa low drag high efficiency hull shape, and for a more experienced sailorcould provides some of the excitement of sport sailing. An increasedangle of heel beyond a desirable angle will result in the wing 74contacting the water on the leeward, or downwind, side of the boat.

These vestigial wings on the upper hull sides provide at least fourcritical advantageous effects on the moving boat. First, and as with the79er when the leeward side wing makes contact with the water due toexcessive heeling it provides a sudden increase in the wetted surface ofthe hull and so a sudden increase in the resistance to forward motion onthe side of the boat in contact with the water. The increased frictionof the water on the added hull surface in the water on the leeward sidecauses the boat to slow and somewhat to leeward when the wing enters thewater. This frictional slowing force is predominantly on one side of theboat and is in a direction to resist broaching of the boat, as follows.

As the wind blows against the boat 40, it exerts a turning force, orwind vane effect, on the boat, also termed broaching force. During highwind conditions, the broaching forces may be quite strong. For a windpowered craft, broaching normally causes the boat to “round up” orrotate toward the wind, while heeling heavily to leeward and thenstalling and laying over at an angle in the water. In extreme cases theboat may experience a full knockdown, in which the boat is fully on itsside with the sails in contact with the water. The additional hullcontact with the water by the wing 74 on the leeward side creates dragthat provides a force to counteract the broaching force. In a powerfulwind gust then the sailboat 40 tilts over, the wings 74 scrub the water,and broaching is resisted. Furthermore, except in the case of extremelypowerful wind gusts, a full broach or knockdown may be entirelyprevented.

Thus, the present invention is a hull design that has inherentanti-broaching characteristics. In conditions that would cause asimilarly sized sailboat to broach, round-up, or take a full knock-downthis hull will heel hard to leeward, stall and come to a halt in thewater abruptly while laying over with the leeward wing under the water(See FIG. 17 of the sailboat stalled during a moderate broaching gust).As can be seen from FIG. 17 of the boat in an actual wind gust stall,the crew have not lost control and are still in their normal crewpositions in the cockpit (crew can often be thrown from their normalcrew positions in a broach, particularly in a small sailboat or dinghy).Once a gust passes or the crew has time to release the pressure on themainsail sheet the craft will tend to right itself and can be sailed outof the stalled condition.

A second effect of the wing 74 contacting the water is that the wing 74changes the hull shape presented to the water from the easy to rollrounded shape of the lower hull to a shape similar to a fin. This finshape must push the water out of the way to move through the water andso provides a strong resistance to further heeling or tilting. Thisshape change results in forces on a relatively long lever arm to resistfurther heeling once the wing 74 is in the water. With reference againto the 79er, this craft will also exhibit anti-broaching properties whenits wings suddenly enter the water. But because the wings are much widerand increase in width much less gradually from the bow, they will have amuch more extreme and less controlled effect when entering the waterthan the wings in the current invention. As mentioned previously thewings on the 79er are primarily for crew leverage to permit a moreextreme sail plan be carried. The leeward wing is therefore not normallyintended to be continuously in contact the water.

A third effect of the wing 74 in contact with the water is that the wing74 provides floatation forces, or buoyancy. Not only does the floatationforce resist movement into the water, but it also provides a rightingforce to bring the boat up to a lesser heeling angle. The rightingforces are also exerted on a relatively long lever arm by virtue of thedistance of the wing from the center of the boat. These effects combineto provide a strong righting moment to not only resist further heelingor rolling of the boat, but to bring the boat to a more upright positiononce sail forces are reduced either by releasing the sheets, or by windforces dropping as happens after a powerful wind gust. As such, eventhough the present boat is a fast, sporty handling boat, the wings 74provide resistance to rolling beyond a predetermined angle, or so-calledover-heel. Consequently, the hull strongly resists capsizing and thusdelivers an important increase in safety. Again referring to the 79er,its wings will also resist further heeling once in the water, but aregenerally much thinner with less buoyancy. Furthermore, since the 79erhull and wings is more like a thin saucer shape it will permit water toenter the large cockpit when heeled at higher angles so further reducingbuoyancy and increasing heel. This is very similar to the action of asaucer floating on water that when tipped at just the right angle tobring the saucer's lip below the waterline will allow water to enter thesaucer.

An added benefit of the wings in the current invention is that, becauseit resists over heeling, the leeward wing 74 serves as a guide to theextent of heel angle to strive for by the crew, in order to avoid thepower loss that results from over-heeling. Once a wing is in contactwith the water, but at less than broaching forces, a greater sail areais being presented to the wind than would otherwise be the case withoutthe wings. With less wind power lost over the top of the sail, there ispotentially greater power and therefore greater speed available to acrew skilled in counterbalancing the dragging force of the wing in thewater to just match the heeling force of the sails without over heeling.In contrast the crew of a 79er would avoid the wings from beingcontinuously in contact with the water because of the more extreme andsomewhat uncontrolled braking affect of its wings in the water.

Finally, and key for improved hull efficiency at higher speeds, theunderside of the wings preserve the convex shape started at the bow tocontinue to encourage vortex creation as the water moves back and upfrom the bow and provides the space needed to accommodate the flow ofdisplaced water less impeded by the unnecessary re-collision with thewidening hull common in most displacement surface craft. In contrast,the Australian 18 and the 79er hulls are not designed or shaped togenerate vortices at the bow or continue to encourage and sustain themalong the undersides of the wings. These hulls are designed to planeeasily and so spend most of their time planing. In a planing conditionthe first 4 to 6 feet or even more of these hulls is often well out ofthe water and has no affect on the wave making of the hull. Both hullsare more dart or V-shape when viewed from above and the rear sectionsare quite flat to promote easy planning.

The wings 74 are readily apparent in FIG. 9, which is a bottom view ofthe hull 42 tipped to an angle as seen by the water during sailing. Themain body 68 is rounded and extends up to the sides 78. From the sides78, the wings 74 extend outward to provide the additional hull surfaceduring over-heeling. The wing 74 has only a minimal extension from theside 78 near the front of the boat, as indicated at 80. At the midpointand to the rear of the boat, the flare or wing 74 has a much greaterextension, as is apparent at 82 and 84. By tapering the wing 74 fromsmaller to larger, a gradual change of shape is presented to the waterto prevent strong resistance from the wing 74 contacting the water. Thewings 74 are of a shape and structure so that the wings can be incontact with the water and the water can flow against the wings whilethe boat is in a normal sailing operation. For example, no abrupt shapechanges are made that would disrupt the flow of water and unduly effectcontrol or operation of the boat when the wing 74 contacts the water orenters the water.

As apparent from FIG. 9, the hull 42 has a widest portion at 86approximately two-thirds of the way back from the bow 58 to the stern.From the widest portion 86 to the stern 60, a gradual inward tapering ofthe hull 42 is provided at the portion below the water line, at thegunnel 72 and the side portions 78. The widest portion 86 defines theover all width or maximum beam of the hull 42. It is also possible thatthe hull maintain this full width beam all the way to the stern insteadof tapering to a narrower width.

The stern 60 is shaped to have a more flat or slightly roundedtermination 88 at the portions below the water line and is angled atside portions 90 that extend from the rail or gunwale 72. The water linelength of the boat is thereby greater due to the extension of the stern60, which increases the maximum potential speed of the boat duringdisplacement travel.

Still with reference to FIG. 9, the front of the hull 42 has sides 89that spread the water after it has been pushed apart by the sharp edge64. The sides 89 are at a relatively shallow angle relative to oneanother to provide a slicing effect at water entry. The rolling motionof the water discussed in conjunction with FIG. 1 forms two rolls orvortices of water that are moved apart from one another by the sides 89.

In a power boat version of this hull shape these rolls of water willnormally be formed symmetrically on either side of the hull. In thissail powered version however the roll will be more pronounced on theleeward side of the hull because of the tendency of the hull to bepushed to leeward by the force of the wind. These rolls of water orvortices continue along the sides of the hull 42 as the boat movesforward, smoothing the movement of the boat through the water andchanging the character of the wave along the sides of the hull duringmovement, particularly during fast movement.

The rolling motion of the water away from the hull and the shape of thehull creates a trough in the water and the hull moves along this trough.The trough shape in the water carries behind the boat and does notimmediately close around the stern of the boat (see FIG. 18 wherein thestern wave is shown). This lessens the drag that would occur otherwiseand is possibly removing or partially removing the stern wave trap thatlimits a displacement hull's theoretical maximum speed. At least asjudged from early-on water testing carried out with the prototype, thetrough shape appears to have the effect of lengthening the effectivewater line of the boat and so increasing the maximum displacement speed.

Further on-water testing is required to verify this potentialbreakthrough capability of the hull shape. FIG. 19 shows a prototypesailboat according to this invention in high speed travel inapproximately 18 to 22 knots of wind, wherein the boat is traveling atan unmeasured speed perhaps somewhere between 8 to 11 knots, but in anyevent above the maximum displacement hull speed for an 18 foot hull.Since the hull is fully in the water over its entire length it appearsto still be operating as a displacement craft.

At the time of writing it is not known for certain that this hull is infact traveling above its normal maximum displacement speed as suggestedby the photographs, nor what mechanism might be at work to accomplishthis property of the hull. The inventor speculates two alternativegeneral explanations for how this hull appears able to travel above thenormal maximum displacement speed without obvious planing. First,although the hull appears to be in displacement mode because the entirehull is in the water, it may in fact be planing, or partially planningwith inception of planing occurring at low hull speeds well before thenormal maximum displacement speed is reached. Alternatively, the hullmay be operating in a displacement mode but the vortices of watercreated at the bow, and encouraged by the convex shaped wing undersides,are separating from the hull surface after passing the widest point ofthe hull and traveling away from the hull at the stern. This mightprevent, or at least inhibit, formation of the full normal stern wave,and thereby allow the hull to at least partially escape the normaldisplacement wave trap.

The limited experimental results so far may favor the second possibilitybecause, as shown in FIG. 20, at even higher speeds, the bow does risesup, and clearly exhibits the inception of normal planing behavior. Also,as shown in FIG. 18 there is a trough evident in the water behind theboat which is not immediately filled in and remains behind the boat forseveral boat lengths. This trough has been observed under most sailingconditions with this hull, and may be supporting evidence that thevortices of displaced water are traveling away from the boat in such amanner as to reduce, inhibit or even eliminate stern wave creation.

The inventor has no special knowledge of vortices, but conjectures thatthe encouragement and creation of vortices may take more energy from thewave shaping forward sections of the hull, but reduces energy taken fromthe aft sections, with a net reduction in energy needed to displace thewater with vortices versus without them. In other words, the totalenergy taken from the hull to first create and then sustain the vorticesmay be lower than the total energy needed to just splash or push asidethe water in the somewhat chaotic manner occurring with most other hullshapes. Perhaps vortices then are capable of moving fluids in a moreefficient manner than with normal fluid movement. This seems areasonable possibility, since vortices once created tend to beself-sustaining, and naturally occurring vortices such as tornados orwaterspouts usually only break up upon encountering obstacles or changesin environment sufficient to extract enough energy from the vortices tocause their collapse.

Returning now to the detailed hull description, the rolling vortices ofwater moving along the sides of the hull 42 move below the convex undersurface of the wings 74. Any momentary tipping of the boat to the sidemay cause the rolling water to contact the wings 74, resulting in astabilizing effect on the boat during movement. While being very tenderat rest, the present hull provides increasing dynamic stability withincreasing speed, and as such provides a very stable hull for the crewwhen underway at speed. This is due in part to wings 74 interacting withthe rolling motion of the water at the sides of the hull 42, and due inpart to the trough formed in the water by the vortex-encouraging shapeat the front and upper sides of the hull 42.

In FIG. 10, the shape of the hull 42 at the bow 58 corresponds to theprinciple discussed in FIG. 2. The bow 58 and the portions of the hullbelow are shaped to help ride over waves rather than through them,providing better handling and crew comfort in a seaway. As stated, hulllength affects maximum displacement hull speed in normal hulls andtherefore the spoon bow potentially sacrifices some speed potential overa plumb bow because of the inherent reduction in waterline length.However, a traditional spoon bow is judged essential in a smallsailboat, because it will usually be sailed in shallow waters and inclose proximity to shorelines. A spoon bow allows the boat to be run upon a beach or shore or handle an unexpected grounding with much lesspotential for damage than a plumb bow. Also, during sailing, oneoccasionally strikes floating debris or even obstacles such as rocks andthe like. Notwithstanding the foregoing advantages of a spoon bowparticularly for small sailboats, a hull with a more vertical, or plumbbow, but with similar concave bow wave shaping surfaces and side wings,is envisaged in a further embodiment and encompassed within the scope ofthis invention.

The front portion of the hull 42 will naturally try to ride over thedebris and rocks or at least lift up on them rather than striking theseobjects with a blunt blow and risking damage to the bow of the boat.Thus damage to the hull 42 is less likely as a result of the present bowshape. The main body 68 of the hull has the rounded bottom portion belowthe water line, as is apparent from the densely spaced contour line atthe bottom of the hull from about midway to the stern 60. Thecross-sectional shape of the hull is also apparent in the FIG. 10 byexamining the section lines 87. The section lines 87 near the front orbow 78 have a sharp angle at the lower end indicating the sharply angledwater line entry of the hull 42, whereas the section lines 87 near themiddle portion and at the rear of the hull 42 have a rounded lowerportion indicating the rounded shape that promotes ready heeling of thesailboat hull.

The shaping of the back sections of the hull 42 promotes planing on thewater at higher speeds, rather than displacement motion. The bow shapeprovides lift in addition to slicing the water during forward motion.The lift is carried back along the hull so that the shallow rounding ofthe hull 42 from the main body 68 to the stern 60 permits the hull 42 toplane on the water upon reaching the planing speed. By providing aplaning hull, the boat 40 is able to exceed its theoretical maximumdisplacement hull speed.

As with all other planing hull designs, planing speed occurs when thehydrostatic forces are just sufficient to lift the hull partially fromthe water, thereby reducing hull drag and also the amount of waterneeding to be displaced. Thus when a watercraft reaches its planingspeed, the situation is equivalent to an aircraft just at the point oflift-off, the aircraft having reached its so-called “rotation velocity”,and above which the pilot may initiate take-off. In a sailboat anyfurther application of power available from the sails will cause thehull to climb over its own bow wave and skim across the waters surfaceexactly like a windsurfer, increasing the speed of the boat beyond itstheoretical maximum displacement hull speed.

FIG. 11 shows the stern 60 of the hull 42 from an end view. The stern 60includes the stern sides 90 shaped with the upper edge at an angle, thesides 90 providing a connection between a rear panel 92 of the hull 42and a step 94 that forms the extension of the hull below the water lineand thereby increases the water line length. The step 94 has ahorizontal top surface 96 and a vertical end surface 98. A roundedcorner connects the vertical and horizontal surfaces 98 and 96. The stepsurface 96 provides a surface on which to kneel and stand to enter theboat, particularly useful for someone entering from the water. Forexample, someone swimming or falling from the boat may re-enter byclimbing onto the step 94. As with other open transom boats with a sternstep, a crew member who accidentally falls into the water may easilyre-board via the step, turning a potential problem into aninconvenience.

Normally in boats of this size the boat crew would re-enter from thewater at the sides. This can prove difficult under heavy conditions,since the boat may heel excessively as the person pulls his weight overthe side. Furthermore, in a small dinghy or boat of this size,re-boarding from the sides can often result in capsize. In contrast,even a person weighing 300 pounds or more could enter from the sternwithout risk of significantly disturbing the boat's attitude in thewater. The rudder 46 is typically mounted on or near the vertical endsurface 98 at the stern 60 and may also provide a structure that can begrasped by the person in the water while pulling up to enter the boat.It is preferred that the top surface of the step 96 be provided with atexture, such as roughening, ridges or grooves, or the like to providemore sure footing for the person entering the boat from the water.

The wings 74 can be seen at the port side of the hull 42 in FIG. 11.Also apparent is the open transom. The rear panel 92 closes only the endof the hull body and does not close the end of the cockpit or crew area100 of the boat. No transom board closes off the end of the cockpit 100as is the case with many boats of this size. This eliminates the risk ofswamping from a large wave entering the cockpit, because any water thatgets into the cockpit 100 may flow out of the cockpit 100 at the stern60 of the boat. The cockpit 100 is preferably shaped with a slope toenable the water to flow readily out the cockpit 100, so that the waterfrom spray, splashes and waves does not remain in the cockpit. The step96 is below the lowest point in the cockpit 100 to allow for easierboarding, and to permit the water to exit more readily, although it isalso possible that the step may be even with the lowest point in thecockpit, just so long as water is not trapped in the cockpit 100.

The opening in the rear panel 92 for the cockpit 100 is in a widened Wshape. This is the shape of the cockpit going forward from the stern 60.The W shape has outer walls or side walls 102 and a center beam 104. Theside walls 102 of the cockpit 100 are curved inward to provide a lowerback support for crew sitting sideways in the cockpit. The center beam104 is angled up to a center ridge line 106 that runs the length of thecockpit 100. Crew members sitting sideways in the cockpit 100 can sit onone side of the center beam 104 and their feet against the side wall 102on the other side with their knees over the center beam 104. The crewmembers are thereby braced between the sidewalls 102. The W shape of thecockpit floor is designed to work well for children 4 feet tall nearerthe front, to adults over 6 feet tall nearer the stern.

The boat 40 has a deck 108, that is also visible in FIG. 11. The deck108 is on either side of the crew compartment, or cockpit, 100 andprovides a seating surface for the crew while sailing at steeper heelangles. The deck 108 extends from the gunnel 72 to the cockpit 100 andis generally flat with a slight camber to direct water off the sides ofthe boat. The deck 108 extends fully over the wings 74 so that any crewsitting on the side portions of the deck with their feet under hikingstraps running down the center of the cockpit floor has a strong leverarm for their body weight to help counterbalance the heeling force ofthe wind. The crew can sit upon the more outboard portion of the deckover the wings without having to hang over the edge of the boat as faras is common in many sailboats. This position is more comfortable andsafer for the crew, with less chance of falling in the water.

For sailing conditions that require the crew to sit up on the side deck108, the crew can place their feet under the hiking straps and restingeither on the opposite sidewall 102 or on the center beam 104 on thesame side on which they are sitting. The center beam 104 therebyprovides a stable foot position for the crew in this position as well.As the wind conditions change, the crew may move to several differentpositions in the cockpit 100 and on the side deck 108 for optimumsailing position, facilitated by the unique W shaping of the cockpit.

Turning now to FIG. 12, the cockpit 100 when viewed from above has aelliptical shape with a elliptical shaped edge 110 where the deck 108and cockpit 100 meet. The cockpit 100 provides the interior space of theboat for the crew during slower sailing or in lighter wind where theheel angle is less. The elliptical shaping of the cockpit 100 reducesthe swamp volume of the cockpit over the more common rectangular shape.Perhaps more importantly, the elliptical shape also forces the majorityof the water toward the stern, aiding in tilting the boat aft to assistrapid draining out of the boat at the open transom. Also as a result ofthe elliptical shape of the cockpit, the deck 108 has a wider seatingsurface for the crew at the midpoint of the boat for greater crewcomfort.

The cockpit surface 104 may have open-able panels 112 for storage withinthe hull 42. For example, an insulated ice chest opening 112 may beprovided for storage of chilled drinks for the crew in the center beam82. It is also preferred that a storage compartment beneath a panel 112be provided for emergency equipment such as a whistle, lifesaver, ropeand the like. Of course, other openings for storage or the like are alsopossible in the center beam 104, in the sidewalls 102 or in the deck108. Such cockpit openings should be of relatively small volume and alsodrained into the trunk to prevent build up of weight due to watertrapped in these enclosures.

The deck has a forward portion 108 on which or in which is mounted themast 48 for the sailboat.

With reference to FIG. 13, the hull 42 is formed of a lower hull piece120 and a deck or upper hull piece 122. The cockpit 100 may be formed inone piece with the deck piece or may be separate. Although these piecesmay be of several different materials, in a preferred embodiment thelower hull piece 120 and the upper hull piece 122 are formed ofcomposite fiberglass and foam sandwich that is molded and shaped to theappropriate shape.

Between the lower and upper hull pieces 120 and 122 is an interior space124 for the boat 40. Preferably, this space 124 includes floatationmaterials, such as foam blocks, air bladders, wood blocks or the like.In a particularly preferred embodiment, the interior space 124 is filledwith a combination of spheres 126 of polystyrene foam and a (pour-able)plastic foam 128 filled in the spaces between the spheres 124. Becausepolystyrene is much lighter than typical marine floatation foam, theeffect of the polystyrene spheres is to reduce the total weight of thecombined floatation material, without leaving air cavities that may bedisplaced by water in a hull breach. Almost the entire interior space124 within the boat 40 is filled with this combination of spheres andfoam. A small space or cavity is left at the bottom of the hull to allowwater from condensation to collect and subsequently be drained. Also afew places are left unfilled to accommodate beverage storage boxes andemergency equipment storage.

The combination of spheres and foam is designed to remain embedded andsecurely attached to the hull or deck. The spheres of polystyrene andthe foam have excellent buoyancy; if the boat were completely fracturedapart in a catastrophic collision, the spheres and foam combinationwould for the most part remain intact and provide powerful floatationforces even to a such a badly fractured hull. The expanded plastic foam128 between the spheres 126 bonds the spheres 126 in place. This lightand strong floatation material, present in almost the entire hull in apreferred embodiment, virtually eliminates the risk of water enteringthe interior space 124, even in the event of a severe hull breach.

In addition to its powerful floatation properties, this mix ofpolystyrene spheres and foam adds strength to the overall structure, andpermits the craft to tolerate multiple sharp object hull penetrationswith a low short-term risk to overall hull integrity and crew safety.Such a structure might even absorb bullets in craft designed formilitary applications. During manufacture, the polystyrene spheres 126,together with the flotation foam, may be preformed in multiple sectionsto fit in to the various cavities of the hull interior, and then bebonded in place to the hull or deck.

In one embodiment, the spheres are about two to four inches in diameter,although other sizes are envisioned and are encompassed within the scopeof this application. Mixed sizes of spheres can be provided as well. Acombination of smaller spheres and larger spheres may be includedtogether to provide greater packing density, or to best fit the specifichull interior cavities. The present invention encompasses the use ofnon-spherical foam pieces in place of the spheres, or in addition to thespheres. These non-spherical pieces can be oval, oblate, square,rectangular and many other shapes. They may also be complex shapes, suchas to fit into specific spaces within the interior space of the hull.Within the scope of this invention, these shapes are encompassed withinthe term sphere.

The spheres are preferably of expanded polystyrene, although other typesof foam or other buoyant material are also possible for use as spheres.Hollow plastic spheres may also be substituted as desired, althoughthese carry a greater risk of water uptake through puncture or osmosis.The foam filler may be liquid foam that expands as it cures, such as anexpanding urethane liquid foam material. It is also contemplated to usefoam particles, flakes, granular foam or other material as the fillerinstead of, or in addition to, the liquid foam. The preferred fillermaterial is pour-able, although this is not necessary. In an alternativeembodiment, the spheres and/or the foam fill may be made of or includewood particles or other buoyant materials. The foam material should be aso-called closed cell foam to reduce water absorption.

The spheres and foam fill may entirely fill the interior space of thehull or may be provided only at portions of the hull. It is preferredthat sufficient spheres and foam be provided in each major section ofthe hull that a catastrophic breakup of the boat will still leave allmajor portions of the hull floating. Persons involved in such a disasterwill have large buoyant pieces of the boat to cling to, and so increasetheir chances of survival.

The present boat is nearly impossible to sink. The hull is strong enoughto take hard impacts without being breaking apart. Even a major hullbreach should not result in sinking of the boat, but will only reducethe speed at which the boat can sail, so that the crew can return toport safely. If a catastrophic event occurs, such as a high-speed impactfrom another boat that fractures the hull into multiple pieces, eachmajor piece should remain floating, providing surviving crew withflotation pieces to cling to until rescued.

The use of the polystyrene spheres 126 with the foam fill 128 reducesthe total weight of floatation material that would be otherwise neededto fill in the interior hull space. The result then is a light boat thatis essentially a solid object, leaving little or no air inside the hullfor water to displace following any hull breach.

Thus, there is shown and described a hull for a sailboat (as shown inFIG. 21 from the starboard side) which is essentially a solid objectthat is lighter than water, and so does not rely on interior air forfloatation. Therefore, unless trapped under a heavier object, thedescribed hull is almost impossible to sink. Furthermore, the hull shapeis designed to move through the water with low resistance, andincorporates side wings to provide wide hiking and seating surfaces, andto powerfully aid stability at speed through increasing roll resistancewith increasing heel angle. The unique hull shape is designed toencourage and aid the creation of vortices along the sides of the boatusing the water that must be displaced anyway. These vortices in-turnstabilize the boat by making contact with the side wings at higherspeeds and heel angles. The present boat is sufficiently fast that thesize of the sails can be reduced compared to boats of similar size, yetstill retain adequate speed from the wind. The smaller sails makesailing easier for the crew, particularly in heavy weather, and make fora lighter boat. The result is a safe, high performance hull designed, inthis first embodiment, in a sports boat that can operate in heavier seaand weather conditions than other boats of its size.

Although other modifications and changes may be suggested by thoseskilled in the art, it is the intention of the inventor to embody withinthe patent warranted hereon all changes and modifications as reasonablyand properly come within the scope of his contribution to the art.

1. A hull for a boat, comprising: an exterior hull surface of the hullhaving a shape that is symmetrical about a longitudinal center line; abow portion of said exterior hull surface having a water entry edge,said water entry edge defining a curve having a horizontal and avertical component, said bow portion including sidewalls having aconcave shape on either side of said water entry edge; a main bodyportion of said exterior hull surface connected to said bow portion,said main body portion having a semicircular shape in transverse crosssection; an upper edge of said exterior hull surface having a deckportion connected thereto; and first and second wings of said exteriorhull surface extending laterally from opposite sides of said hull belowsaid upper edge, said first and second wings having a greater extent oflateral extension at a mid-portion of said hull than at said bow, saidfirst and second wings being structured to permit water to flow againstthe wings while under normal sailing operation.
 2. A hull as claimed inclaim 1, wherein said first and second wings taper from a full lateralextension at sides of a midpoint of said hull to a slight lateralextension adjacent said bow.
 3. A hull as claimed in claim 1, furthercomprising: a stern of said exterior hull surface defining a rearwardextension of said exterior hull surface at a lower portion thereof andhaving an endwardly tapering sidewall between said upper edge and saidlower portion.
 4. A hull as claimed in claim 3, wherein said sternincludes a step, said step including a horizontal step surface extendingtransversely across stern and a vertical surface below said step surfacedefining a rearmost surface of said hull.
 5. A hull as claimed in claim1, further comprising: a stern of said exterior hull surface defining arearward extension of said exterior hull surface, said rearwardextension being tapered to said longitudinal center line and rising toabove a water line of the hull.
 6. A hull as claimed in claim 1, furthercomprising: a cockpit formed in said deck, said cockpit defininginterior side surfaces extending from said deck, said interior sidesurfaces being curved inwardly and being adapted for a crew member tosit leaning against said interior side surfaces; and a center beamextending longitudinally of said hull in said cockpit.
 7. A hull asclaimed in claim 6, wherein said deck includes side deck portionslaterally of said cockpit, said side deck portions overlaying saidwings, said side deck portions being adapted for a crew member to situpon.
 8. A hull as claimed in claim 1, further comprising: foam spheresin an interior space between said exterior hull surface and said deck;and foam material filled between said foam spheres, said foam materialbonding said foam spheres in place.
 9. A hull as claimed in claim 8,wherein said foam spheres are of polystyrene.
 10. A hull as claimed inclaim 1, wherein said hull is a sailboat hull.
 11. A hull as claimed inclaim 1, wherein said hull is a powerboat hull.
 12. A hull for asailboat, comprising: an exterior hull surface of the hull having ashape that is symmetrical about a longitudinal center line; a bowportion of said exterior hull surface having a water entry edge, saidwater entry edge defining a curve having a horizontal and a verticalcomponent, said bow portion including sidewalls having a concave shapeon either side of said water entry edge; a main body portion of saidexterior hull surface connected to said bow portion, said main bodyportion having a semicircular shape in transverse cross section; anupper edge of said exterior hull surface having a deck portion connectedthereto; and first and second wings of said exterior hull surfaceextending laterally from opposite sides of said hull below said upperedge, said first and second wings having a greater extent of lateralextension at a mid-portion of said hull than at said bow, said wingsextend from both sides of said hull, said wings tapering from a fulllateral extension at sides of a midpoint of said hull to a slightlateral extension adjacent said bow; a stern of said exterior hullsurface defining a rearward extension of said exterior hull surface at alower portion thereof and having an inwardly tapering sidewall betweensaid upper edge and said lower portion, said stern including a step,said step having a horizontal step surface extending transversely acrossstern and a vertical surface below said step surface defining a rearmostsurface of said hull; a cockpit formed in said deck, said cockpitdefining interior side surfaces extending from said deck, said interiorside surfaces being curved inwardly and being adapted for a crew memberto sit leaning against said interior side surfaces; a center beamextending longitudinally of said hull in said cockpit; said deckincluding side deck portions laterally of said cockpit; said side deckportions overlaying said wings, said side deck portions being adaptedfor a crew member to side upon; foam spheres in an interior spacebetween said exterior hull surface and said deck; and foam materialfilled between said foam spheres.
 13. A hull for a boat, comprising: anouter hull of fiberglass; an inner hull of fiberglass, said inner hullbeing mounted in and connected to said outer hull to define an interiorspace there between; foam spheres in said interior space; and a foammaterial between said foam spheres in said interior space, said foammaterial bonding said foam spheres in place.
 14. A hull as claimed inclaim 13, wherein said hull is a sailboat hull.
 15. A hull as claimed inclaim 13, wherein said hull is a powerboat hull.
 16. A hull as claimedin claim 13, wherein said inner hull includes a deck and a cockpit. 17.A hull for a boat, comprising: an exterior hull surface of the hullhaving a shape that is symmetrical about a longitudinal center line; abow portion of said exterior hull surface having a water entry edge,said water entry edge including a front edge defining a substantiallystraight line that is substantially perpendicular to a water surface assaid hull is floating on the water, said bow portion including sidewallshaving a concave shape on either side of said water entry edge; a mainbody portion of said exterior hull surface connected to said bowportion, said main body portion having a semicircular shape intransverse cross section; an upper edge of said exterior hull surfacehaving a deck portion connected thereto; and first and second wings ofsaid exterior hull surface extending laterally from opposite sides ofsaid hull below said upper edge, said first and second wings having agreater extent of lateral extension at a mid-portion of said hull thanat said bow.
 18. A hull for a boat, comprising: an outer hull portionhaving a bow and stern; a cockpit in said outer hull portion, saidcockpit having a shape in transverse cross-section generally in a shapeof a W, said W shape extending generally from said stern to at leastcrew seating area of said cockpit; and a deck extending from outer edgesof said cockpit to upper edges of said outer hull.
 19. A hull for a boatas claimed in claim 18, wherein said cockpit has a generally ellipticalshape when viewed from above, said W shaped being defined in part by abeam extending along a central axis of said parabolic shape.
 20. A hullfor a boat as claimed in claim 18, wherein said outer hull portionincludes wings extending laterally from both sides of said hull portion,said wings gradually increasing in extent of extension from said sidesbeginning with a minimal lateral extension adjacent said bow and agreater extension at a position midway between said bow and said stern,said deck defining seating surfaces above said wings.